WO2011156980A1 - Steel and train hook made therefrom - Google Patents

Abstract

The invention discloses a steel and a train hook made therefrom. The steel composition comprises, in wt%, C: 0.24%-0.32%; Si: 0.20%-0.50%, Mn: 1.30%-1.70%, P≤0.020%, S≤0.020%, Cu≤0.30%, Cr: 0.50%-0.80%, Ni: 0.40%-0.70%, MO: 0.25%-0.45%, Al: 0.02%-0.08%, and the balance Fe and inevitable impurities. The invention provides the steel having high strength and excellent toughness. The steel mechanical properties are better than the mechanical properties of Grade E Steel.

Description

 Steel and its made hooks

 The present invention relates to metallurgical techniques, and more particularly to a steel having higher mechanical properties and a coupler made therefrom. Background technique

 With the development of the industry, the mechanical properties of steel materials are increasingly demanding. For example: In the development of "speeding up and heavy load" of railway wagons, the total towing weight of railway wagons has increased greatly, and the manufacturing quality requirements for truck parts have become higher and higher; the couplers are used as connecting parts between trucks, in trucks. It bears large tensile stress and impact force; the knuckle of the coupler is a weak part of the truck, which is prone to breakage during the operation of the truck. The fracture of the knuckle during the operation of the truck is usually fatigue fracture, and the occurrence of fatigue fracture includes the poor toughness of the material of the knuckle or insufficient material strength reserve.

 Therefore, in order to meet the growing industrial demand, for example, in order to improve the fatigue life of the coupler, it is necessary to increase the strength and toughness of the steel. Summary of the invention

 It is an object of the present invention to provide a steel and a coupler therefor to improve the mechanical properties of the steel, particularly to increase the strength and toughness of the steel, and to provide a coupler having good mechanical properties.

 In order to achieve the above object, the present invention provides a steel comprising the following components: carbon, 0.24-0.32% by weight; silicon, 0.20-0.50% by weight; manganese, 1.30-1.70% by weight; phosphorus, weight Percentage is < 0.02%; sulfur, weight percent < 0.02%; copper, weight percent < 0.30%; chromium, weight percent 0.50-0.80%; nickel, weight percent 0.40-0.70%; molybdenum, weight percent 0.25 -0.45%; aluminum, 0.02-0.08% by weight; balance is iron and other unavoidable elements.

 Wherein, the weight percentage of the carbon is preferably 0.25 to 0.29%, more preferably 0.25 to 0.28%. The weight percentage of manganese is preferably from 1.35 to 1.60%, more preferably from 1.35 to 1.55%.

The weight percentage of the hydrazine is preferably <0.015%. The weight percentage of the ^ is preferably <0.015%.

 The weight percentage of the aluminum is preferably 0.02 to 0.06%, more preferably 0.02 to 0.05%.

 In order to achieve the above object, the present invention also provides a coupler made of the steel provided by the present invention. The steel provided by the invention and the coupler made thereof have the advantages of high strength and good toughness, and the mechanical properties are higher than the standards of the existing E-grade steel. detailed description

 The technical solution of the present invention will be further described below in conjunction with specific embodiments.

 The present invention provides a steel comprising the following components: carbon, 0.24-0.32% by weight; silicon, 0.20-0.50% by weight; manganese, 1.30-1.70% by weight; phosphorus, % by weight < 0.02% Sulfur, weight percent < 0.02%; copper, weight percent < 0.30%; chromium, weight percent 0.50-0.80%; nickel, weight percent 0.40-0.70%; molybdenum, weight percent 0.25-0.45%; , the weight percentage is 0.02-0.08%; the balance is iron and other unavoidable elements.

 Among them, the weight percentage of carbon is preferably 0.25 to 0.29%, more preferably 0.25 to 0.28%. The weight percentage of manganese is preferably from 1.35 to 1.60%, more preferably from 1.35 to 1.55%. The weight percentage of phosphorus is preferably < 0.015%. The weight percentage of the stone carp is preferably < 0.015%. The weight percentage of aluminum is preferably 0.02 to 0.06%, more preferably 0.02 to 0.05%.

 The weight percentage of silicon is preferably from 0.20 to 0.40%, more preferably from 0.21 to 0.39%. The weight percentage of chromium is preferably from 0.50 to 0.65%, more preferably from 0.50 to 0.60%. The weight percentage of nickel is preferably from 0.40 to 0.60%, more preferably from 0.40 to 0.55%. The weight percentage of molybdenum is preferably 0.25 to 0.35%, more preferably 0.25 to 0.30%.

The chemical composition of steel basically determines the mechanical properties of steel materials. The smelting process provides a good foundation for the subsequent treatment of materials by improving the purity of molten steel and reducing the content of gases and harmful elements. The heat treatment process after smelting process can excavate materials. The greatest potential for mechanical properties. Therefore, to improve the mechanical properties of steel, chemical composition is crucial. Among them, carbon and manganese are the main elements to improve the strength of the material; reducing the content of strontium and S of harmful elements, and appropriately increasing the nickel content, is conducive to improving the toughness of the material; appropriately increasing the content of manganese, chromium and molybdenum can improve the hardenability of the material. At the same time, the increase of molybdenum content can effectively inhibit the temper brittleness of the material; the content of aluminum can be controlled in the subsequent heat treatment. Refine the grain in the middle.

 The present invention also provides a coupler made of the steel provided by the present invention. The coupler has high mechanical properties, high strength, good toughness, and can withstand large tensile stresses and impact forces. The coupler can be used in a variety of scenarios, such as: for railway wagons or railway passenger cars. Experimental example

 The chemical compositions of Experimental Examples 1-1 to 1-10 of the steel provided by the present invention are shown in Table 1; Experimental Examples The mechanical properties of the steels of 1-1 to 1-10 are shown in Table 2. Among them, the heat treatment process of Examples 1-1 to 1-10 is an existing heat treatment process, that is, a quenching and tempering process (including quenching and tempering processes): the quenching temperature is

910 °C, holding time is 2 hours, water quenching; tempering temperature is 560 °C, holding time is 3.5 hours, air-cooled.

 Table 1

表 2

Table 2

由表 1和表 2可知， 本发明提供的钢的力学性能都远高于 E级钢， 屈 服强度比 E级钢的标准提高了约 20%, 抗拉强度比 E级钢的标准提高了约 13%, 冲击功比 E级钢的标准提高了约 90%, 延伸率和断面收缩率也远高 于 E级钢； 其中， 冲击功越高， 表示钢的韧性越好。

It can be seen from Table 1 and Table 2 that the mechanical properties of the steel provided by the present invention are much higher than those of the E-grade steel, and the yield strength is improved by about 20% compared with the standard of the E-grade steel, and the tensile strength is improved by about the standard of the E-grade steel. 13%, the impact energy is about 90% higher than that of E-grade steel, and the elongation and reduction of area are much higher than that of E-grade steel. Among them, the higher the impact energy, the better the toughness of steel.

 Among them, the American AAR (American Railway Association) M201 standard divides steel into the following grades according to the strength from low to high: Grade A steel, B grade steel, B+ grade steel, C grade steel, E grade steel. The highest grade is grade E steel.

Due to the above chemical composition, the steel provided by the invention has good mechanical properties, high strength, good toughness, and mechanical properties higher than that of the E-grade steel. In order to further improve the mechanical properties of the material, the steel material of the present invention can be obtained, in particular, by a heat treatment process comprising a preliminary heat treatment and a quenching and tempering heat treatment process on the smelting product, the preliminary heat treatment being normalized treatment, and the quenching and tempering heat treatment process For quenching and tempering The process may specifically include the following steps:

 Step 1. Preheating the steel, wherein the normalizing temperature is 900-960 ° C, the holding time is 3-5 hours, air cooling or air cooling; wherein the normalizing temperature is preferably 920-950 ° C, more preferably 930-950 ° C, the holding time is preferably 3.5-4.5 hours, more preferably 4 hours;

 Step 2. The quenching treatment is performed on the steel subjected to the preliminary heat treatment in the step 1, the quenching temperature is 900-920 ° C, the holding time is 2-3 hours, and the cooling method is water quenching;

 Step 3: Tempering the steel subjected to quenching in step 2, the tempering temperature is 520-580 °C, the holding time is 3-5 hours, and the cooling method is water cooling; wherein the tempering temperature can also be 550- 570 °C, or 530-550 °C.

 The steel provided by the invention can eliminate the as-cast structure of the steel, refine the crystal grains, and prepare the structure for the quenching and tempering heat treatment, and the water is cooled in the tempering treatment to eliminate the temper brittleness, the mechanics of the steel. Performance has been significantly improved.

 The steel smelting process is also included prior to the heat treatment of the steel. The smelting process can utilize existing smelting processes, for example, the following steps can be included:

 Step a, preparation of raw materials; According to the composition requirements of the smelting steel, the iron alloy required in the smelting process is weighed and sent to the furnace of the electric arc furnace, and at the same time, various slagging materials, recarburizing agents, oxidizing materials, reducing materials Uniform delivery to the furnace.

 Step a2, charging; scraping, sorting, size and weight according to the requirements of the furnace, according to "large, medium, small, light", into the furnace hopper, with the addition of carbonizer and some ferroalloy After the feeding is carried by the battery car, after weighing, it is loaded into the electric arc furnace in batches.

 Step a3, electric current melting; after the scrap steel is charged into the electric arc furnace, it can be electrified and melted.不同Different currents and voltages are used to convert electrical energy into heat to melt the scrap into molten steel. In order to speed up the melting process, the oxygen blowing and melting process can also be used during the energization process.

 Step a4, oxidation; after the scrap steel is melted into molten steel, the slag-forming material is added to cover the surface of the molten steel with a layer of slag. When the temperature of the molten steel is appropriate, an oxidizing material is added, and the molten steel is boiled by the reaction of carbon and oxygen to remove the steel. Gas in water. Since the molten steel has boiled, the molten steel is in full contact with the slag, and the harmful elemental phosphorus in the molten steel is transferred to the slag. The molten steel composition can be detected 2-3 times during oxidation. At the end of the oxidation period, the ladle can be baked.

Step a5, slag; at the end of oxidation, stop when the composition and temperature meet the process regulations Electricity, slag in the oxidizing period to prevent harmful elemental phosphorus from entering the molten steel again.

 Step a6, reduction; After the slag in the oxidizing period, the electricity is sent and quickly added to the slag-forming material, and the oxygen element in the molten steel is removed by diffusion deoxidation and precipitation deoxidation, and the iron alloy is added in order according to the degree of easy oxidation of the iron alloy. To the molten steel. During the reduction process, the inert gas is stirred to cause the molten steel to flow and to be in full contact with the slag, and the harmful elemental sulfur in the molten steel is transferred to the slag. While deoxidizing, desulfurizing, and adjusting the composition of molten steel, it also continuously raises the temperature of molten steel to prepare for tapping.

 Step a7, tapping; Under the premise that the molten steel composition is qualified, the molten steel temperature and the ladle baking are in accordance with the process regulations, and the molten steel deoxidation test is good, the steel can be cut off.

 Step a8, refining the molten steel; during the tapping process, the inert gas is blown into the ladle and kept for a certain period of time. After the end of the tapping, the deoxidizer is fed into the ladle. In order to ensure the reliability and safety of high-intensity running vehicles, ore producers have put forward higher requirements on the mechanical properties of materials used as couplers. This requirement is higher than that for E-grade steels. The following steels will meet this requirement. See E+ grade steel, the mechanical properties of E+ grade steel are shown in Table 3.

 table 3

 As shown in Table 3, the mechanical properties of E+ grade steel are higher than that of E grade steel. The yield strength and tensile strength of E+ grade steel are 10% higher than those of E grade steel, and the impact energy is 20% higher than that of E grade steel. .

E-grade steel (Experimental Examples 2-1 to 2-10) was used, and the existing heat treatment process was used to obtain the mechanical properties of the E-grade steel. Among them, the raw materials in Experimental Examples 2-1 to 2-10 may be commercially available E-grade steel, or may be E-grade steel which is produced by the manufacturer according to the requirements of the E-grade steel. Table 4

 Among them, the existing heat treatment process for obtaining E-grade steel parts is as follows: quenching treatment temperature is 910 ° C, holding time is 2 hours, water quenching; tempering temperature is 560 ° C, holding time is 3.5 hours, air cooling.

 It can be seen from the data in Table 4 that as the strength (yield strength and tensile strength) increases, the impact energy (toughness) index of the E-class steel decreases and becomes unstable, and the mechanical properties are qualified compared with the requirements of the E+ grade steel. The rate is only 50%.

The steel of the new composition provided by the present invention (Experimental Examples 3-1 to 3-10) was used. After the smelting process, the heat treatment process provided by the present invention was carried out, and the mechanical properties of the finally obtained steel were shown in Table 5. table 5

 Among them, the specific components of the steel in Experimental Examples 3-1 to 3-10 are shown in Table 6.

 Table 6

3-8 0.28 0.37 1.46 0.011 0.012 0.57 0.55 0.28 0.08 0.05

3-8 0.28 0.37 1.46 0.011 0.012 0.57 0.55 0.28 0.08 0.05

3-9 0.27 0.39 1.47 0.010 0.012 0.58 0.53 0.30 0.09 0.04

3-10 0.29 0.40 1.50 0.014 0.012 0.61 0.49 0.32 0.08 0.05 As shown in Table 5, the steel of the new composition provided by the present invention has a mechanical property significantly higher than that of the E+ grade steel by the heat treatment process provided by the present invention. (especially impact work), the pass rate reached 100%. Compared with the existing E-grade steel shown in Table 4, the steel provided by the present invention has much higher mechanical properties than the E-grade steel.

 It can be seen from the data of Tables 5 and 2 that the steel with the new composition provided by the present invention has a significantly improved mechanical property after a special heat treatment process (Table 5) than when only the existing heat treatment process is performed, especially in When the strength is not lowered, the impact work is greatly improved. That is, the steel having the new composition provided by the present invention can improve the toughness without lowering the strength or even increasing the strength.

 The invention provides a steel material with high strength and good toughness, and the steel material can be applied in various aspects, for example, as a coupler for railway wagons, to meet the needs of railway trucks for "speeding up and heavy loading".

 It should be noted that the above embodiments are only for explaining the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that: The technical solutions described in the foregoing embodiments are modified, or some of the technical features are equivalently replaced. The modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

Rights request  A steel characterized by comprising the following components: Carbon, weight percentage is 0.24-0.32%; Silicon, weight percentage is 0.20-0.50%; Manganese, the weight percentage is 1.30-1.70%; Phosphorus, weight percent < 0.02%; Sulfur, weight percent < 0.02%; Copper, weight percent < 0.30%; Chromium, weight percentage is 0.50-0.80%; Nickel, weight percentage is 0.40-0.70%; Molybdenum, the weight percentage is 0.25-0.45%; Aluminum, weight percentage is 0.02-0.08%; The balance is iron and other inevitable elements.  2. Steel according to claim 1, characterized in that the weight percentage of carbon is 0.29%.  3. Steel according to claim 2, characterized in that the weight percentage of carbon is 0.28%.  4. The steel according to claim 1, wherein the manganese is 1.60% by weight.  5. Steel according to claim 4, characterized in that the weight percentage of manganese is 1.55%.  6. The steel according to claim 1, wherein the weight percentage of the crucible is <%. 7. The steel according to claim 1, wherein the weight percentage of the sulfur is <%. The steel according to claim 1, wherein the aluminum has a weight percentage of .06%. The steel according to claim 8, wherein the aluminum has a weight percentage of .05%.  A coupler made of the steel of any of claims 1-9.